Photocatalytic degradation of nonylphenol by immobilized TiO2 in dual layer hollow fibre membranes

Abstract

Nonylphenol (NP) is one of refractory degradation intermediates of nonylphenol ethoxylates (NPEO) surfactant and among the most toxic and prevalent endocrine disrupting compounds (EDCs) found in the environment. This paper reports an effort in removing nonylphenol in water using novel photocatalytic dual layer hollow fibre membrane, where the outer layer comprised of polyvinylidene fluoride (PVDF)/titanium dioxide (TiO2) while the inner layer was 100% PVDF. Single layer hollow fibre membrane which consists of PVDF/TiO2 was also fabricated as the control sample. The presence of TiO2 on the outer surface of both dual and single layer hollow fibres was confirmed by scanning electron microscopy (SEM), energy dispersion of X-ray (EDAX) and contact angles analysis. The removal of 85% in NP concentration was achieved for dual layer hollow fibre after 4h UVA irradiation in submerged membrane photoreactor, compared to 70% for the single layer one. The kinetic rate of dual layer membranes was calculated to be 0.0092min−1 against 0.0062min−1 for the single layer counterpart. In general, dual layer hollow fibre membranes exhibited superior photocatalytic performance in comparison to single layer hollow fibre membranes due to the better dispersion of TiO2 on the outer membrane surface.